Tether Offload HAL

Adds new interfaces to perform hardware optimized tethering offload.

Test: as follows
    - built (bullhead)
    - flashed
    - booted
    - "runtest frameworks-net" passes
Bug:34361337
Change-Id: I1ed756306e1efe98bd2703df9c9846a50a87ffcd
diff --git a/tetheroffload/config/1.0/IOffloadConfig.hal b/tetheroffload/config/1.0/IOffloadConfig.hal
new file mode 100644
index 0000000..4d285da
--- /dev/null
+++ b/tetheroffload/config/1.0/IOffloadConfig.hal
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.hardware.tetheroffload.config@1.0;
+
+
+/**
+ * Interface used for configuring the hardware management process
+ */
+interface IOffloadConfig {
+  /**
+   * Provides bound netlink file descriptors for use in the management process
+   *
+   * @param fd1   A file descriptor bound to the following netlink groups
+   *              (NF_NETLINK_CONNTRACK_NEW | NF_NETLINK_CONNTRACK_DESTROY).
+   * @param fd2   A file descriptor bound to the following netlink groups
+   *              (NF_NETLINK_CONNTRACK_UPDATE | NF_NETLINK_CONNTRACK_DESTROY).
+   *
+   * @return success true if successful, false otherwise
+   * @return errMsg a human readable string if eror has occured.
+   */
+  setHandles(handle fd1, handle fd2) generates (bool success, string errMsg);
+};